Cost Estimator Get a Quote
Quantity Surveying & Budget Planning

Domestic Build Budget Estimator

Indicative cost guidance for house extensions, loft conversions, and private domestic refurbishments based on prevailing UK labour and materials benchmarks.

Project Specification

Configure Parameters

40 m²
15 m² (Small Galley) 40 m² (Kitchen Diner) 80 m² (Large Wrap-around) 150 m² (Bespoke New Build)
Indicative Bracket

Estimated Total Investment

Direct contractor pricing including structural steelwork, installation, fit-out, and site management.

Total Estimated Bracket (inc. VAT):
£115,000 - £130,000
Estimated Duration: Approx. 16 - 19 Weeks
  • Core Construction & Materials: £92,500
  • Architectural & Structural Calcs (approx 10%): £9,250
  • Statutory UK VAT (20%): £18,500
  • Fixed-Price JCT Contract: Standard
  • 10-Year Insurance Warranty: Included

Binding quotes provided in writing by RAZ CONSTRUCT LIMITED following an on-site survey.

Market Guidance

Average UK Domestic Construction Benchmarks

Project Classification Typical Area Indicative Bracket (excl. VAT) Duration Planning Route
Single Storey Rear Extension 25 - 35 m² £50,000 - £80,000 10 - 14 Weeks Permitted Development
Wrap-Around Ground Floor Extension 40 - 55 m² £95,000 - £145,000 14 - 18 Weeks Full Planning Permission
Rear Dormer Loft Conversion 25 - 35 m² £42,000 - £65,000 6 - 10 Weeks Permitted Development
Mansard Loft Conversion 35 - 45 m² £68,000 - £98,000 8 - 12 Weeks Full Planning Permission
Full Period House Renovation 120 - 200 m² £140,000 - £260,000 16 - 24 Weeks Building Regulations Only
+44.7460064914